Schistosome dermatitis in lake wanaka: Cercaria longicauda prevalence in lymnaea tomentosa, 1978–83

Abstract

Results of a study undertaken between 1976 and 1983 suggest several conditions are necessary for Cercaria longicauda to cause swimmers’ itch in Lake Wanaka. These are water temperatures in excess of 13°C, the presence of beds of the water plant Isoetes alpinus with sediment on the leaves, and the presence of the two hosts: the water snail Lymnaea tomentosa, and the New Zealand scaup Ay thy a novaeseelandia. The release of the dermatitis causing cercariae is spasmodic and restricted to summer. Cercariae were released only from snails more than 3 mm long. © Crown 1988.